package day07;

import java.util.Random;

/*
*需求:生成?位验证码(大写字母,小写字母,数字)
 */
public class VerificationCode {
    public static void main(String[] args) {
    String code = generateVeriCode(3);
        System.out.println("验证码:"+code);
}
public static String generateVeriCode(int len){
    String code = "";
    char[] chs = {'a','b','c','d','e','f','g','h','i','j','k','l', 'm',
            'n','o','p','q','r','s','t','u','v','w','x','y','z','A','B',
            'C','D','E','F','G','H','I','J','K','L','M','N','O','P','Q',
            'R','S','T','U','V','W','X','Y','Z','0','1','2','3','4','5',
            '6','7','8','9'};
    Random rand = new Random();
    for(int i= 1;i<=len;i++){
        int index = rand.nextInt(chs.length);//随机下标(0-9,A-Z,a-z)
        code += chs[index];//获取随机字符并拼接到code中
    }
    return code;
    }
    /*
     i=1    index = 0   code=a
     i=2    index = 6   code=af
     i=3    index = 34  code=afH
     i=4    index = 49  code=afH0
     i=5
     */
}